Hard x-ray sources have been available for nearly 110 years, with a well-established and extraordinary impact on science and technology. From the dozen or more Nobel Prizes recognizing their role in fundamental discovery in chemistry and physics to the medical x-ray, which virtually every citizen of modern developed countries has experienced, x-rays have yielded unparalleled benefits to modern society.
In the last thirty years, the production of extremely high brilliance x-ray beams by accelerator-based sources (i.e., synchrotron radiation) has revolutionized the field of x-ray science and technology. The impact of these sources is comparable with that of the original discovery of x-rays. Using these high-brilliance x-ray beams, scientists are able to (a) see single atomic layers, (b) use weak-magnetic scattering routinely, (c) study dynamic phenomena using inelastic and time-dependent techniques with extraordinary resolution, and (d) spectroscopically probe complex molecules with extremely high resolution. Perhaps the largest impact is coming from “structural genomics”—the application of novel synchrotron-radiation-based diffraction methods to solve the full, three-dimensional, atomic-level structure of all known proteins. In the field of imaging science, synchrotron sources have allowed the much-more-subtle angle and energy shifts, which occur as an x-ray penetrates a material, to be the basis for differentiating different material constituents in an image. This method is known as phase-contrast imaging. Remarkable improvements in image resolution and lowering of dose are now well known. Nevertheless, the scientific impact of these sources is now limited by their gigantic size, which leads to their high cost (i.e., over a billion dollars in some cases) and relative scarcity. Virtually everyone who does research at the synchrotron user facilities does so under extremely limiting conditions of travel and available beam time.